FRANKFURT (REUTERS) -- Porsche named Bernhard Maier on Monday as new head of sales and marketing for its 51 percent-owned sports car unit with immediate effect, replacing Klaus Berning.

Porsche said in a statement that Berning was leaving at his own request. A spokesman said the departure was amicable for both sides.

The German news magazine Der Spiegel reported on Saturday that Berning fell out with Porsche AG CEO Michael Macht and key labor representatives, in part due to poor vehicle sales.

Porsche AG, the sports car maker that is 49 percent owned by Volkswagen, declined to comment on the report.

Its volumes fell 24 percent to 75,238 units in the fiscal year to end-July. They slid a further 1.7 percent to 33,670 in the first half.

Maier, 50, joined Porsche in June 2001, managing its domestic sales subsidiary and went on to successfully launch in the German market the Cayenne offroader in 2002 and the Panamera four-seater last year.